Method of fiberizing asbestos



0d. 9, 1945. W 1 JQYCf-gy JR 2,386,401

METHOD OF FIBERIZING ASBESTOS Filed Jan. 24, 1944 Patented Oct. 9, 1945METHOD F FIBERIZING ASBESTOS William J. Joyce, Jr., Manheim, Pa.,assignor to Raybestos-Manhattan, Inc., Passaic, N. J., a corporation ofNew Jersey Application January 24,1944, Serial No. 519,580

l0 Claims. (Cl. 191) chrysotile form being of most predominantoccurrence and production, and also of,most usefulness due to itscontent of ilne, long fibres of high tensile strength. The value ofasbestos lies primarily in the length of its fibres, the ability tocard, spin and weave it, and the ability to produce therefrom variousmaterials such as yarn, cloth, felt, tape, paper, miilboard and many'speciilc products well known in the art. Thus,

Vwhat is commercially known as Ithe grade of the libre refers not to thesource or variety but to the fibre length, No. 1 grade having a lengthof about one inch or more.

Heretofore asbestos has been subjected to crushing. beating or otherwisemechanically manipulated to open and separate the ilbres with the end inview of making them line and lit for carding, spinning and weaving, orgood dry and wet felting. However, such mechanical processes inherentlyand in varying degree cause reduction in natural libre length with theresultant production of commercially excessive lines and dust.

It is therefore an object of the present invention to iiberize or openasbestos in a simple but novel and highly edective manner which isconducive to the production of a maximum amount of fibers of high grade,that is of good length substantially equal to the natural length of thefibers, by what is essentially a physical method, as distinguished fromchemical or mechanical methods.

In general my method comprises the explosive fiberization of asbestos ineither rock or partially crushed form by conning it in a pressurechamber or vessel or gun together with a gaseous medium, which is inertwith respect to asbestos, under pressure,- and subsequently suddenlyreleasing the pressure whereby the asbestos is ejected and the fiberbundles subdivided along their natural lines of cleavage without tearingor changing their length substantially.

Other objects and advantages will be apparent from a consideration ofthe following specification and accompanying drawing whichdiagrammatically illustrates an arrangement of apparatus for carryingout my invention.

Referring to the drawing, the reference numeral I0 indicates a pressurechamber or gun" the smallest internal diameter of which, including thatoi its inlet port II and outlet port I2, is sufilciently great to handlethe introduced asbestos in its natural fiber length. The asbestos to beberized is introduced from a suitable hopper I3 through a valve Id, andis ejected through quickopening valve I5, the valve apertures beinglikewise of suicient dimension to permit straightthrough introduction,and particularly ejection of the asbestos in its natural fiber lengthwithout causing bending or pressure which will shorten the length of thefibres or break the material as it discharges. A

After the asbestos to be iiberized is introduced to pressure vessel III,and with valves I4 and I5 closed, gas under pressure is introducedthrough line I6 and valve I1. As gaseous agents I may employ air, carbondioxide, nitrogen,v argon, ammonia. sulphur dioxide, steam and the likecompressible fluids, or mixtures thereof which are inert with respect tothe asbestos, under -a high superatmospheric pressure such as fromaboutv 200 to about 1200 pounds per square inch; depending upon thenature of the'asbestos, its condition. that is rock form, crushed,coarse, etc., and the desired degree of fI-berization. I have found, forexample, that a pressure of from about 400 to about 800 pounds persquare inch is a suitable range for good berization of chrysotileasbestos in rock form to produce a finely divided fibrous mass ofpredominantly No. l grade libers. has reached the desired degree, valveI'l is closed and thereafter after a relatively short period ofconfinement, such as from about 5 to 30 seconds, valve I5 is suddenlyfully opened by suitable quick acting means, land the materialexplosively discharged through exhaust line I 8 to cyclone separator I9wherefrom the expanded gas is exhausted upwardly through line 2D and thefiberized asbestos downwardly through exhaust line 2 I.

For the purpose of quickly or suddenly opening valve I5, I may, asillustrated couple the valve stem 22 thereof through a gear segment andrack 23 to an air cylinder 24, the cylinder being connected through theinlet line 25 and exhaust line 26 to the quick acting air valve 2l, airunder low pressure being admitted to the .valve 21 through line 28 andexhausted through line 29, the valve actuation being controlled throughthe hand lever 30.

As indicated, my process requires only the application under pressure ofa gas inert with re- After the pressure within the vessel I0 l spect toasbestos, the term gas being understood to include a vaporous materialsuch as steam, and the quick release of the pressure and discharge ofthe material. The process may be carried out with or without thepresence of moisture and/or heat. In the employment of steam the vessellll may -be suitably insulated or even heated to avoid loss of pressureor undue condensation. The presence of moisture or water resulting fromthe use of steam, or otherwise, causes the material to be ejected in amore or less tangled wetted mass of fibers. However, as indicated, thepresence of moisture or heat, or pre-softening or heating of theasbestos, is not necessary to the successful operation of my process andI preferably operate with dry ashes# tos and a dry gas, under normalroom temperature conditions, to obtain a finely iiberized product, thefibers being separated along their natural lines of cleavage and ofsubstantially natural liber length.

I claim as my invention:

l. The method of fiberizing unflberized or partially iiberizedcrystalline masses of asbestos to produce asbestos fibers of a desiredsubstantially uniform fineness and without substantial change in theoriginal natural length of the fibers, which comprises: confining theasbestos aggregates in a closed zone together with a gaseous mediumchemically inert with respect to asbestos under a superatmosphericpressure sufof the desired substantially uniform fineness, andrecovering the resulting iiberized asbestos.

4. The method of fiberizing unberized cr partially fiberized crystallinemasses of asbestos to produce asbestos fibers of a desired substantiallyuniform fiberization and Without substantial change in the originalnatural length of the fibers, which comprises: confining the asbestosaggregates in a closed zone together with a gaseous medium chemicallyinert with respect to asbestos under a'superatmospheric pressuresufficient to eiect flberization but insufficient to cause detrimentalreduction in fiber length, releasing the pressure suddenly to expel theasbestos from' the closed zone into a zone of lower pressure tosubdivide said aggregates into fibers of the desired substantiallyuniform fineness, and

recovering the resulting iiberized asbestos.

2. The method of flberizing uniiberized or partially flberizedcrystalline masses of asbestos to produce asbestos fibers'of a desiredsubstantially uniform flneness and without substantial change in theoriginal natural length of the fibers, which comprises: confining theasbestos aggregates at substantially normal temperature in a closed zonetogether with a gaseous medium chemically inert with respect to asbestosunder a superatmospheric pressure suilicient to effect berization butinsufficient to cause detrimental reduction in fiber length, releasingthe pressure suddenly to expel the asbestos from the closed zone into azone of lower pressure to subdivide said aggregates into fibers of thedesired substantially uniform fineness, and recovering the resultingflberized. asbestos.

' 3. The method of fiberizing unfiberized or partially flberizedcrystalline masses of asbestosy to produce asbestos fibers of a desiredsubstantially uniform fineness and without substantial change in theoriginal natural lengthv of the fibers, which comprises: confining theasbestos aggregates in a closed zone together with a substantially drygaseous vmedium chemically vinert with respect to asbestos under asuperatmospheric pressure sumcient to effect fiberization butlnsuiiicient to cause detrimental reduction in liber length, releasingthe pressure suddenly to expel the asbestos from the closed zone into azone of lower pressure to subdivide said aggregates into bers about 30seconds.

iicient to effect fiberlzation but insufficient to cause detrimentalreduction in fiber length, releasing the pressure suddenly to expel theasbestos from the closed zone into a zone of lower pressure to subdividesaid aggregates into bers of the desired fineness and of substantiallyuniform fiberization, and recovering the resultingr iiberized asbestos.

5. The method of iiberizing uniiberized or partially flberizedcrystalline masses of asbestos to produce asbestos fibers of a desiredsubstantially uniform fineness and without substantial change in theoriginal natural length of the fibers, which comprises: confining theasbestos aggregates at substantially normal temperature in a closed zonetogether with a substantially dry gaseous medium chemically inert withrespect to asbestos under a superatrnospheric pressure sufficient toeffect fiberization but insufficient to cause detrimental reduction inber length, releasing the pressure suddenly to expel the asbestos fromthe closed zone into a zone of lower pressure to subdivide saidaggregates into fibers of the desired substantially uniform neness, andrecovering the resulting fiberized asbestos.

6. The method of fiberizing unberized or parl tially iiberizedcrystalline masses of asbestos to produce asbestos fibers of a desiredsubstantially uniform flneness and without substantial change in theoriginal natural length of the fibers, which comprises: confining theasbestos aggregates in a closed zone together with a gaseous mediumchemically inert with respect to asbestos under a superatmosphericpressure sufiicient to effect fiberization but insuilicient to causedetrimental reduction in fiber length, releasing the pressure suddenlyto expel the asbestos from the closed zone into a zone of lower pressurethrough an opening having a minimum dimension at least equal to themaximum natural fiber length of the asbestos being fberized and tosubdivide said aggregates into fibers of the desired substantiallyuniform fineness, and recovering the resulting fiberized asbestos.

7. The method claimed in claim 1 wherein the pressure ranges from about200 to about 1200 pounds per square inch.

8. The method claimed in claim 1 wherein the pressure ranges from about400 to about 800 pounds per square inch.

9. The method claimed in claim 1 wherein the gaseous medium comprisesessentially compressed air. l

l0. The methodclaimed in claim 1 wherein the asbestos aggregatesA areconfined in the closed zone for a time ranging between about5 `andWILLIAM J. JOYCE, JR.

